i) Field of the Invention
This invention relates to a recirculating device and method for recirculating a stream of fluid from a vessel; the invention also relates to a recirculation conduit assembly which forms a subassembly of a recirculating device of the invention and to a combination of a vessel housing a fluid and a recirculating device of the invention.
ii) Description of Prior Art
One is frequently faced with the situation where it is desirable either to insert a sensor into a closed fluid filled tank to monitor some characteristic of the fluid or to be able to withdraw a representative sample of the fluid from the tank for subsequent analysis. If the tank cannot be emptied, fabrication of a suitable entry port for the sensor, is, in most cases, impossible. Even if such a port does exist, installation of a sensor without significant fluid loss is also difficult or impossible if the fluid level cannot be lowered.
Obtaining a representative fluid sample for independent analysis from a tank fitted only with a drain valve also presents problems since considerable fluid must be discarded to eliminate the stagnant fluid in the region of the valve. Even after such flushing, the final sample will still be taken from near the tank wall which may not be representative of the bulk fluid.
A representative example of this problem is the electrical transformer which comprises a closed tank housing an insulating oil. Such transformers have a long life, typically 20 years or more and most existing transformers are not equipped with an entry port permitting access to the oil for sensing parameters of the oil. Such sensing is now routinely employed as a means of detecting faults in the transformer, see, for example, Canadian Patent 1,082,774, issued July 29, 1980, James E. Morgan. Existing tanks do have a drainage port but removal of a fluid sample through such port results in the disadvantages indicated above.